New Bessey K Body Revo - added force?

[Will Blick]

Just got my first K Body Revo's. Bessey touts:

REVO™ design exerts 25% more clamping force than original K Body®

I tested the Revos against the standard K Bodies with a pressure gauge.... and the ol K bodies slightly out performed the new Revos. About 800 lbs of force with a good grip... maybe 20lbs less with the new Revo. I oiled the Revos up, but to no avail.

Bessey had a great opportunity on this clamp to allow the handle to swivel 90 deg. to gain the added force, and reduce skin blisters, but I guess cost prevented such.

While the new Revo has some slightly better build issues, IMO, the old K bodies are quite the bargain while they still last.

[Jason Beam]

I wondered about that claim, myself. Can you inspect the thread on the two and see if they're at all different? If they didn't change the thread, there's no real logic to their claim. But if they messed with the pitch on that lead screw, they might have a mathematical increase - something they can prove on paper, i guess.

I like my good ole' standard besseys, myself.

[Will Blick]

Can't see any difference in the threads...... I think the claim for greater force came as a result of the synthetic grip..... the problem is, its still close to being round and not much thicker than the wood K body grips..... so no great improvement IMO.

OTOH, the Stanley Bailey's have a super thick grip, in triangular shape.... I can easily drive them to 1100 lbs without ripping my hands apart.... Stanley got the grip right...the entire Baily clamp is VERY impressive.... I bought some 12"'s.... but for longer, I still like the flexibility of the K's, as I can link them together... as well as the Jets.

[Brent Smith]

Hi Will,

I've been wondering about that claim of more clamping power, specifically why was it added (which apparently it was not). as I see it the old K-Bodies have more than enough. If you need to clamp down any harder than that, there's a problem with your joint.

[Anthony Anderson]

as I see it the old K-Bodies have more than enough. If you need to clamp down any harder than that, there's a problem with your joint.

That is what I was thinking Brent. Just like you said, if the joint is prepared properly, then such excessive force will only starve the glue joint. Was also wondering if the Revo clamps had a head that adjusts for angles. I thought I saw that somewhere. Bill

BTW, I really like my original K-Bodys.

[Will Blick]

More bad news... Revo after 30 minutes lost 200 lbs of pressure. Only my bar clamps slip this bad.... maybe because its new, so I will give it time, but not a good sign. Slippage is one of the most overlooked aspects of clamps. Only a gauge will advise you, it's deceiving. Again, the Stanlyes are the best in this category also, after 30 minutes, they barely loose 50 lbs on avg, and considering they are starting at over 1000 lbs of force, quite impressive. As I have mentioned before, I find it amazing that Stanley entered the clamp game so late, and yet, made a killer parallel clamp.


I hate to turn this thread into a "how much pressure" thread. But in short,


1) its almost impossible to starve a joint of glue, no matter how many clamps you use....

(I am tossing a caveat in here.... if you try hard enough, its possible to starve a joint, but its highly improbably based on the number of clamps most people use)


2) Clamping pressure at 200 psi for hardwoods is not ONLY good to get max. holding force when the glue dries, but also provide an invisible glue line. In my case, I chase the invisible glue line more than I do the max. holding force of the glues, as most projects I do are never subjected to the levels of force whereas the joint will fail.... Titebond engineers suggest 250 psi of force for hardwoods to close the glue line just a bit below .002". (invisible)


3) Clamping force is consumed quickly, as the force must be divided by sq inches of the joint.... so to meet Titebonds requirements of 250 psi, (for either invisible glue line and / or max. holding), a 1" thick board glue up, would require one 750 lb force clamp every 3" of glue line. 750 lb force clamps are about avg. for most parallel clamps. Hence why I like to see how much force many of these clamps truly exert.... and how long they hold the pressure. I have a handful of the Gross Stabils that are recently being dumped on the market since Bessey bought GS, and they are the worst of all, avg maybe 450 lbs. Even at half price, they aren't worth it.


Anyway, glue pressure always brings out the stone throwers on these forums.... so use the information to your liking. There is many times, I use blue tape as my clamps, and I have never had a problem, but this is for small moldings or edging..... so like everything else, a bit of common sense has to be applied to each application.

[Alan Schaffter]

Clamping pressure is a subjective term until you define it and when you bring the human element into the equation it makes numbers meaningless.

1. Hand torque and other design features aside and assuming near unlimited strength - since the face of the new Revo is larger (more sq. in.), someone theoretically could apply more total pounds. The object, through the face of the jaw, pushes back with more force than a smaller jaw. Now, since hand torque is limited this argument is totally meaningless.

2. If the claim is based on the amount of torque a person can apply to the handle- Revo has a new handle that ostensibly allows a person to grip it better, without slipping, and to apply more torque- so the clamping pressure is greater than the same individual could apply with the old K-bodies. With a toggle handle parallel jaw clamp you could apply even more torque.

3. The only true way of increasing the clamping force for the same individual using a Revo vs an old K-body is to increase the mechanical advantage, either by using a pivoting (lever) handle like the clamps from (?) or to use a finer pitch on the lead screw.

Bottom line, you can't get something for nothing.

Frankly, if you need to apply more pressure than a K-body can deliver, you made something wrong. The benefit of K-bodies or any of the parallel jaw clamps is (1) the jaws are parallel and (2) the clamping face is the adjustable face unlike a pipe clamp- I always hated adjusting the fixed face end of long pipe clamps.

[Will Blick]

I feared this..... I hope the flames remain low...


> Clamping pressure is a subjective term until you define it

I did define it, by the use of a gauge. Clamps produce force, this easy to measure.



> since the face of the new Revo is larger (more sq. in.), someone theoretically could apply more total pounds.


Clamping force is irrelevant of the clamping surface area. It's the sq inches of the glue line that is divided by the total force.



> If the claim is based on the amount of torque a person can apply to the handle- Revo has a new handle that ostensibly allows a person to grip it better, without slipping, and to apply more torque- so the clamping pressure is greater than the same individual could apply with the old K-bodies.


Agreed....and this is what I tested. My point was, the new handle was an insignificant improvement as for gaining more clamping force. It offered no better grip than the wood handles on the K body. Hence my disappointment. It felt a little better, but offered no more in terms of force. As I mentioned, the Stanley Bailey Parallel clamp got the handle perfect...hence the level of force is so much greater...



> With a toggle handle parallel jaw clamp you could apply even more torque.

I thought for sure Bessey would have done this, if for no other reason, it's easier on your hands and fingers... just like a pipe clamp. I bought a few Bessey Chinese knocks-offs from Woodline, whose handle bent 90 deg., but the damn clamp was so poorly made in other areas, I returned them.



> The only true way of increasing the clamping force for the same individual using a Revo vs an old K-body is to increase the mechanical advantage, either by using a pivoting (lever) handle like the clamps from (?) or to use a finer pitch on the lead screw.


Or a better designed handle, the Stanley Clamps demonstrated this with flying colors, they have the same mechanics as all the others, but will attain 30 - 40% more force.



> Frankly, if you need to apply more pressure than a K-body can deliver, you made something wrong.


You need half the number of clamps for a given glue up, if you use clamps that provide 2x the pressure..... that IMO is a significant issue when choosing what clamps to buy.




> I always hated adjusting the fixed face end of long pipe clamps.


Good point.... OTOH, the it's relatively easy to move the rear standard...and if you use black iron pipe, it reduces slippage.... most pipe clamps can easily apply 1200 lbs of force due to their 90 deg. handle. Considering their low price and the fact you need to use less of them, they are quite the bargain...

[Alan Schaffter]

You might want to go back and fix your font, you are shouting.

The "you" was generic, not "you" specifically. Just go back and read the clamp reviews this year in the WW mags- check out their methods for applying and measuring clamping pressure. One mag said they used members of the staff- not scientific, but actually somewhat relevant, since it gave a range of what was possible by each member using each clamp. How about this rating "Jane Board, a 5'3" female of average build and musculature can apply more force with a Schmotz clamp than with a Squeezit clamp, on Tuesdays, with 5 min. rest between clamping, testing the Schmotz first, and no tail wind" That is about all they can truly say, but does it sound good in a magazine ad? No numbers!?!?! Gotta have numbers!!!!! Unfortunately there is too much human variable for any better.

A gauge will measure force applied to a point, so is not relevant to clamping woodworking, and frankly test the person, not the clamp. One person's grip might be better on a triangular handle than a fluted handle of visa versa.

I was talking theoretical force applied by the clamp face, trying to second guess Bessey's logic or method, not referring to the force applied across a glue line.

Ah, Woodline, thanks, I couldn't remember that vendor. Maybe they patented the toggle handle? Maybe Bessey didn't think they needed the extra leverage?

Now the final point, again, I maintain, if you need more force than a Bessey can apply you have done something wrong or your board warped on you. If you have a long glue line you need even force applied along it, so you need either more clamps to spread the force out over the span regardless of the type of clamp, or you need a totally rigid (steel) backer or use something like a Bow Clamp which claims by its computer designed bowed geometry to accurately spread the pressure out along the glue line and therefore requires fewer clamps. Even edge gluing/clamping wide hardwood boards you need to use multiple clamps or you chance crushing the outer edge wood fibers.

And the real bottom line- they are all WAY OVERPRICED!!!!!!!!!!!!!!!! Glad I got my Besseys during the frenzy of 6 -7 years ago when you could pick up a K31 or larger for around $12-15$.

[Will Blick]

Sorry about the fonts, I can't seem to edit that? Anyway, shouting is CAPS, not slightly larger fonts...


> How about this rating "Jane Board, a 5'3" female of average build and musculature can apply more force with a Schmotz clamp than with a Squeezit clamp, on Tuesdays, with 5 min. rest between clamping, testing the Schmotz first, and no tail wind"


Of course everyone will apply different force....but that is not the real issue. The issue is.... how each clamp reacts differently in its ability to apply force for the same person. So the results between clamps will be relatively the same ratio differences.... i.e. the Stanley applies about 35% more force than the Besseys, regardless if the persons strength...its a relative difference. Also, there is no reason to turn this into an exact science, if you are a man of avg. strength, these numbers are close enough, no one is trying to get within 10% of accurate results, instead, we are trying to avoid 800% mistakes in lack of clamping pressure.


> Now the final point, again, I maintain, if you need more force than a Bessey can apply you have done something wrong or your board warped on you.


Its the total number of clamps you need, which is a factor of how much force each clamp can provide. If you use Bar Clamps vs. GS parallel clamps, you can use 1/3 the number of bar clamps....... it doesn't mean you did anything wrong, you simply need x bar clamps or 3x GS clamps. Less clamps = faster working before the glue dries....not sure what you find combative about this issue?

[Alan Schaffter]

I guess we will have to agree to disagree.

[Will Blick]

Revo at 300 lbs of force after 20 hours.... terrible....

Like a tire with a slow leak....

[Alan Schaffter]

Revo at 300 lbs of force after 20 hours.... terrible....

Like a tire with a slow leak....

Doesn't make sense! Is the handle turning?!??!?!?! If it is then the clamp is bad. If not the gauge tip is compressing the soft jaws, or if wood is involved the fibers are being compressed- technique issue.

[Will Blick]

Alan, the clamp is new...... I will give it a break in period. They all loose tension.... just not this much. Are you under the impression that every new product works perfectly? There is no wood involved, only the clamp and the gauge.... yes, there might be a small amount of compression, but not this much. I will try it a few more times...

The Rockler pipe clamps with the nickel plated bar they sell slips so bad, its barely useful, pressure goes from 1200 lbs to 500 lbs in 30 minutes.... black pipe reduces this 80%.

[Alan Schaffter]

Alan, the clamp is new...... I will give it a break in period. They all loose tension.... just not this much. Are you under the impression that every new product works perfectly? There is no wood involved, only the clamp and the gauge.... yes, there might be a small amount of compression, but not this much. I will try it a few more times...

The Rockler pipe clamps with the nickel plated bar they sell slips so bad, its barely useful, pressure goes from 1200 lbs to 500 lbs in 30 minutes.... black pipe reduces this 80%.

?????
Hmmm, I have NEVER had a Bessey K-Body slip. Really, NEVER. You must have a bad one/batch. My only limitation on clamping pressure using a Bessey K-Body has been the strength of my grip and wrist trying to tighten them.